The present invention relates to a mill for grinding loose materials.
It is known that mills of the gravity or centrifugal-grinding type are used to grind products such as enamels, grits and the like.
These mills contain a plurality of balls which act by gravity or by centrifugal force and break up the material between the balls and/or between the balls and the internal surface of the mill.
These mills suffer some drawbacks, among which the fact that they require disadvantageously long times for introducing, grinding and unloading the materials, require a considerable amount of balls or beads to effectively break up the product contained therein, and allow to grind only specific quantities of the material that is introduced, said quantities being closely linked to the quantity of balls and to the dimensions of said mills.
It can in fact be noted that in the case of conventional gravity mills grinding occurs mainly on the bottom of the mill, whereas in the case of centrifugal mills breakup occurs mainly along the material surface of the mill; accordingly, in both cases it is convenient for the amount of product to be ground to be directly proportional to the number of balls and to the size of the mill in which it is contained.
Furthermore, mills that work by centrifugal force must have very small dimensions, and therefore very small capacities, because they require very high power levels to move the masses.
The aim of the present invention is to eliminate the above drawbacks of conventional mills by providing a mill for grinding loose materials which allows to minimize the quantity of the grinding media for effective breakup, to limit the power level required and the actual time required for introduction, grinding and unloading, and to grind different quantities of material regardless of the dimensions of said mill.
Within the scope of this aim, an object of the present invention is to provide a structure which is simple, relatively easy to be manufactured, safe in use, effective in operation and having a relatively low cost.
This aim, this object and others are achieved by the present mill for grinding loose materials, characterized in that it comprises a closed container which is provided with at least one opening for introducing and removing the materials and has, at its poles, a first coupling shaft and a second coupling shaft articulated thereto, a fixed frame which has centering means for said first shaft, said frame supporting a driving shaft which is actuated so that it can rotate continuously, and a flange which is fixed to said driving shaft and has eccentric means for supporting said second shaft with a rotary coupling element interposed, said eccentric means being adapted to make said second shaft perform a substantially circular orbit.